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Lesson 1

Infrequent Recovery Situations

Imagine a situation like this: Before you manage to complete an open database backup, your system crashes and brings down the database. You cannot open the database because the datafile in the hot backup mode is not synchronized with the database. The following questions must be answered before you proceed.
  1. Does this datafile need a recovery?
  2. What can you do?
Learning how to solve problems like the one above is the focus of this module. You have already learned how to perform complete and incomplete recovery to an ARCHIVELOG database in various situations. There are, however, other occasions when a database or datafiles may need some special attention. Although these situations do not occur frequently, as a DBA you should be prepared for these events.
This module investigates recovery situations that can happen on occasion and provides possible solutions to handle these problems. In addition, the maintenance of online redo logs is covered.
It is important to remember that all topics in this module are for a database running in ARCHIVELOG mode.

Put the Database in ARCHIVELOG Mode

Putting the database in ARCHIVELOG mode (assuming that it is not already) is a simple process, but it does require shutting down the database and then restarting it. Here are the steps for putting the database in ARCHIVELOG mode:
1. Shut down the database:

Module Objectives

After completing this module, you will be able to:
  1. Recover a datafile with no backup
  2. Recover a file in backup mode
  3. Clear a corrupted online redo log file
  4. Perform a recovery with inactive online redo logs
  5. Recreate online redo log files
  6. Obtain recovery status information
The next lesson demonstrates how to recover a lost datafile with no backup.